Many modern integrated circuit fabrication processes utilize plasma etching processes. Referring to FIG. 1, illustratively, in a plasma etching process, a wafer 19 is electrostatically supported by raised portion 15 of base 11. Base 11 is conventionally termed an "electrostatic chuck." Wafer 19 is surrounded by ring 13. Ring 13 is generally termed a "shadow ring". The purpose of the shadow ring is to protect base 11, 15 from the etching effect of the plasma, thereby insuring the chemical purity of the plasma. Typically, shadow ring 13 is made from quartz. Protrusion 21 comprises a silicon insert 23 which rests upon the quartz material of shadow ring 13. FIG. 1 does not show (for clarity) a shower head which is generally positioned above the wafer and the electrostatic chuck. The shower head provides the reactant gases which interact in a plasma to cause etching upon wafer 19.
Those concerned with the development of integrated circuit technology have consistently sought improved apparatus and methods for plasma processing.